BAGHDAD, May 6 -- Two car bombs killed at least 12 people Wednesday in Baghdad, the latest in a series of attacks by insurgents attempting to undermine public confidence in the Iraqi government as the U.S. military begins to withdraw from cities.

The deadlier of the blasts occurred shortly after 7 a.m. in a crowded vegetable market in the Dora neighborhood of southwestern Baghdad. At least 11 people were killed and 37 were wounded by a bomb concealed under bags of produce in the back of a pickup truck, witnesses said.

The other bomb went off around noon in central Baghdad. It apparently targeted, but missed, a police patrol. At least one bystander was killed, according to police.

The wave of attacks in recent weeks has driven up the number of civilian casualties after a months-long decline in violence. But many Iraqis have deemed the lull in violence temporary, and residents at the blast sites Wednesday appeared to take the new attacks in stride.

Under the haze of a sandstorm, police officers in central Baghdad cracked jokes as workers in orange vests swept debris off the street. In Dora, trucks packed with produce continued to arrive at the market, and merchants spent the day cleaning up and preparing to reopen Thursday.

Prime Minister Nouri al-Maliki has played down the recent bloodshed, saying last week that the bombs "don't worry us" because the "days of worry and pain" are gone forever.

He has rejected suggestions that the departure of U.S. troops from urban areas be delayed because of the spate of bombings. Under a bilateral agreement signed last year, American forces are scheduled to leave inner-city posts by June 30.

Top U.S. officials have said the increase in violence will not affect the timeline in the security agreement. But they have adopted a more cautious stance.

Top American military officials recently issued an order barring commanders and spokesmen from using the oft-repeated phrase "security continues to improve," because they deemed it "disingenuous" in light of the recent attacks, according to a U.S. official, who spoke on the condition of anonymity.

Maxim Abdul Ramdan, 25, a vegetable seller at the Rashid produce market, said the truck with the explosives was left at the market overnight.

"There was a rumor among security forces yesterday about car bombs," Ramdan said. "But we didn't know when or where. Nobody paid attention. We always hear these rumors."

The blast was partially buffered by a large truck loaded with eggplant. The explosives shattered a handful of vehicles parked nearby and tore through the market's tin roof. A second bomb in a truck parked just outside the market was defused moments after the first blast, Iraqi police officials said.

Most of the recent attacks have targeted Shiite areas. Dora is a predominantly Sunni district, but most of the produce sellers at the market are Shiites.

So far, however, the bombings do not appear to have triggered retaliatory attacks by Shiite militias. Such counterattacks made violence endemic in Baghdad in 2006 and 2007.

"They want to bring back the sectarian issues," Ramdan said, standing near a three-foot-deep crater created by the explosion. "But they will not succeed. The people standing here now are Sunnis and Shiites."

Special correspondents Qais Mizher and Zaid Sabah contributed to this report.